The present invention relates to a reflection frequency conversion device using an active metamaterial surface capable of converting the frequency of a reflected wave by providing a voltage waveform changed with time, to an active metamaterial surface capable of changing a phase of a reflected wave by coupling a variable capacitor to a high impedance surface (HIS), and an ECM system.
Generally, when it communicates by using an electromagnetic wave, in the majority of cases, the conductor disturbs the communication.
In other words, when an antenna is formed at a PCB substrate, since a metal grounding plate is operated as a shorted circuit from a position of propagation, the reflection coefficient has “−1”. At this time, in case of the reflection coefficient of “−1”, it is reflected in the same size. However, the phase is reversed to 180 degrees. In case of the propagation reflected from the metal grounding plate, it can be seen that the phase thereof is reversed to 180 degrees through the propagation radiated from the antenna to be reflected. Due to this phenomenon, since the offset is generated between the reflected propagation and the propagation radiated from the antenna, it causes the efficiency reduction of the antenna radiation.
In order to minimize the above phenomenon, conventionally, it has been proposed a High-profile antenna using a PCB substrate having a thick thickness more than a predetermined thickness. However, in case of the antenna having the thick PCB substrate, since the thickness of the antenna is increased and the flexibility of the antenna is reduced, it has trouble in producing the antenna of requiring compactness/softening like a cell phone antenna.
In order to minimize these problems, recently, it has been proposed a High Impedance Surface (HIS) structure. In the HIS structure, a resonance phenomenon is generated at certain frequencies through the transformation of a surface structure in that a groove etc. having a periodic structure is formed at the conventional metal grounding plate. Here, the value of the surface impedance of the HIS is infinity at the resonance frequency, unlike the metal in that the value is “0”. Accordingly, the phase of the reflective wave is “0” at the resonance frequency and the phase of the reflected propagation is the same as that of the propagation radiated from the antenna, so that it can enhance the performance of the antenna.
However, the surface impedance characteristic of the HIS is restricted owing to the shape of the metal structure engraved on the substrate.
On the other hand, recently, researches for using as a military purpose in addition to the performance improvement of the antenna for the HIS have been considerably progressed in foreign countries.
In other words, the modern aircrafts have many antennas and the antennas have various purposes such as a jamming, an interception, a communication, and a radar etc.
Accordingly, in order to expand the applicability thereof, it requires a new HIS structure capable of freely transforming the electromagnetic waves flowed on the surface according to the circumstances.